RUTHERFORD, N.J. — The FBI says suspicious materials discovered in packages delivered Friday to multiple hotels and a deli located less than a mile from MetLife Stadium in New Jersey and to former New York Mayor Rudy Giuliani’s office in Manhattan appear to be harmless.

Giuliani told FOX Sports 1 that the package his office near Rockefeller Center received contained “a non-toxic substance,” but that further tests were being done “just to be sure.”

“The building is now operating perfectly normally,” Giuliani said.

A police source told FOX Sports 1 NFL Insider Mike Garafolo that as many as 10 locations are being investigated, and that the packages are believed to have originated in the southern United States. The source also told Garafolo that one of the substances was identified as cornstarch. A federal law enforcement official told The Associated Press that powder from one envelope tested positive for baking soda.